Light source and backlight module having the same

ABSTRACT

A light source includes a carrier, a plurality of solid-state light-emitting devices, a plate photo-coupler, a first reflector, and a plurality of second reflectors. The solid-state light-emitting devices and the light-incoupling component are configured on the carrier. The light-incoupling component has a bottom surface, a top surface, a plurality of side surfaces adjoining the bottom surface and the top surface, and a through hole extending from the bottom surface to the top surface. The solid-state light-emitting devices are located in the through hole. The first reflector covers the through hole. The second reflectors are configured on the side surfaces. Light emitted from the solid-state light-emitting devices enters the light-incoupling component via a sidewall of the through hole and leaves the light-incoupling component via the top surface thereof.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Taiwan applicationserial no. 99137995, filed on Nov. 4, 2010. The entirety of theabove-mentioned patent application is hereby incorporated by referenceherein and made a part of this specification.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a backlight module, and more particularly to adesign of a light source in a backlight module.

2. Description of Related Art

In recent years, liquid crystal displays (LCDs) that have been developedto achieve full-color display gradually replace conventional cathode raytube (CRT) displays and have become mainstream displays in the marketdue to the advantages of low operation voltages, non-radiation, lightweight, small volume occupancy, and so forth. The LCDs arenon-self-illuminating displays, and therefore display functions of theLCDs are achieved when the required light is provided by backlightmodules. With increasing consciousness of environmental protection, coldcathode fluorescent lamps (CCFLs) serving as light-emitting devices inconventional backlight modules are gradually replaced by light-emittingdiode (LED) devices that are more friendly to the environment.

FIG. 1 is a schematic cross-sectional view illustrating a conventionalbacklight module. With reference to FIG. 1, a conventional backlightmodule 100 includes a light guide plate (LGP) 110, a plurality of lightsources 120, and a plurality of optical clear adhesives 130. The LGP 110has a light-incident surface 110 a and a light-emitting surface 110 bopposite to the light-incident surface 110 a. Each of the light sources120 is adhered to the light-incident surface 110 a of the LGP 110 viaone of the corresponding optical clear adhesives 130, respectively.

As shown in FIG. 1, each of the light sources 120 includes a carrier 120a, a plurality of LED devices 120 b, a light-incoupling component 120 c,and a plurality of ring-shaped reflectors 120 d. The LED devices 120 band the light-incoupling component 120 c are configured on the carrier120 a. Light emitted from the LED devices 120 b enters thelight-incoupling component 120 c from side surfaces S of thelight-incoupling component 120 c and leaves the light-incouplingcomponent 120 c from a top surface T of the light-incoupling component120 c. The ring-shaped reflectors 120 d cover the LED devices 120 b andan edge of the top surface T. Besides, the top surface T of thelight-incoupling component 120 c is adhered to the light-incidentsurface 110 a of the LGP 110 via the optical clear adhesive 130.

As indicated in the region X of FIG. 1, the light emitted from the lightsource 120 in FIG. 1 is excessively concentrated on top of thelight-incoupling component 120 c. In addition, a part of the lightemitted from each of the LED devices 120 b passes through thecorrespondingly optical clear adhesive 130 and is then reflected by thesidewall of each of the ring-shaped reflectors 120 d, which causes lightleakage as indicated in the region Y of FIG. 1. Accordingly, theconventional backlight module 100 has unfavorable optical uniformity,and said problem requires an effective solution.

SUMMARY OF THE INVENTION

The invention is directed to a light source and a backlight module thathave favorable optical characteristics.

The invention provides a light source that includes a carrier, aplurality of solid-state light-emitting devices, a plate photo-coupler,a first reflector, and a plurality of second reflectors. The solid-statelight-emitting devices and the light-incoupling component are configuredon the carrier. The light-incoupling component includes a bottomsurface, a top surface, a plurality of side surfaces adjoining thebottom surface and the top surface, and a through hole extending fromthe bottom surface to the top surface. The solid-state light-emittingdevices are located in the through hole. The first reflector covers thethrough hole. The second reflectors are configured on the side surfaces.Light emitted from the solid-state light-emitting devices enters thelight-incoupling component via a sidewall of the through hole and leavesthe light-incoupling component via the top surface thereof.

According to an embodiment of the invention, the carrier is a circuitboard, for instance.

According to an embodiment of the invention, the solid-statelight-emitting devices are side-view LED packages, for instance.

According to an embodiment of the invention, each of the solid-statelight-emitting devices has a light-emitting surface, and each of thelight-emitting surfaces faces the sidewall of the through hole.

According to an embodiment of the invention, a shape of the firstreflector and a shape of the through hole are substantially the same.

According to an embodiment of the invention, the through hole includes acircular through hole, an elliptical through hole, or a polygonalthrough hole.

According to an embodiment of the invention, the sidewall of the throughhole includes a plurality of curved surfaces.

According to an embodiment of the invention, the first reflector is areflective plate, and the first reflector and the top surface of thelight-incoupling component are substantially on the same plane.

According to an embodiment of the invention, a gap is between the firstreflector and the solid-state light-emitting devices.

According to an embodiment of the invention, the second reflectorsinclude a plurality of reflective plates or a plurality of reflectivecoatings.

According to an embodiment of the invention, the light source canfurther include an optical filler that fills the through hole andencapsulates the solid-state light-emitting devices. A refractive indexof the optical filler is different from a refractive index of the platephoto-coupler.

According to an embodiment of the invention, the light source canfurther include a third reflective layer configured between the carrierand the bottom surface of the plate photo-coupler. For instance, thethird reflective layer is a white sheet.

The invention further provides a backlight module that includes at leastone light source described above, an LGP, and at least one optical clearadhesive. The LGP has a light-incident surface and a light-emittingsurface opposite to the light-incident surface. The first reflector ofthe light source and the top surface of the light-incoupling componentare adhered to the light-incident surface of the LGP via the opticalclear adhesive.

According to an embodiment of the invention, a top/bottom surface of theLGP has a plurality of optical micro-structures, and the opticalmicro-structures are dots, V-cuts, or other optical micro-structuressuitable for scattering light, for instance.

The solid-state light-emitting devices are configured in the throughhole of the plate photo-coupler, and the first reflector covering thethrough hole and the second reflectors configured on the side surfacesof the light-incoupling component allow the light to be emitteduniformly from the top surface of the light-incoupling componentaccording to this invention. Hence, the light source and the backlightmodule mentioned above have favorable optical characteristics.

To make the above and other features and advantages of the inventionmore comprehensible, several embodiments accompanied with figures aredetailed as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide further understanding,and are incorporated in and constitute a part of this disclosure. Thedrawings illustrate exemplary embodiments and, together with thedescription, serve to explain the principles of the disclosure.

FIG. 1 is a schematic cross-sectional view illustrating a conventionalbacklight module.

FIG. 2A is a schematic bottom view illustrating a backlight moduleaccording to an embodiment of the invention.

FIG. 2B is a schematic cross-sectional view illustrating a backlightmodule according to an embodiment of the invention.

FIG. 2C is a schematic top view illustrating a light source according toan embodiment of the invention.

FIG. 3 is a schematic view illustrating a light-incoupling componentaccording to another embodiment of the invention.

FIG. 4 is a schematic cross-sectional view illustrating a backlightmodule according to another embodiment of the invention.

FIG. 5 shows comparison between optical characteristics according to therelated art and according to an embodiment of the invention,respectively.

DESCRIPTION OF EMBODIMENTS

FIG. 2A is a schematic bottom view illustrating a backlight moduleaccording to an embodiment of the invention. FIG. 2B is a schematiccross-sectional view illustrating a backlight module according to anembodiment of the invention. FIG. 2C is a schematic top viewillustrating a light source according to an embodiment of the invention.With reference to FIG. 2A to FIG. 2C, the backlight module 200 of thisembodiment includes an LGP 210, one or more light sources 220, and oneor more optical clear adhesives 230. The LGP 210 has a light-incidentsurface 210 a and a light-emitting surface 210 b opposite to thelight-incident surface 210 a. Each of the light sources 220 is adheredto the light-incident surface 210 a of the LGP 210 via one of theoptical clear adhesives 230, respectively. In this embodiment, thenumber of the light sources 220 in the backlight module 200 can beproperly adjusted based on actual product requirements. For instance,when the backlight module 200 is applied to a small-scale LCD panel, thebacklight module 200 can have a single light source 220. By contrast,when the backlight module 200 is applied to a medium-scale or alarge-scale LCD panel, the backlight module 200 can have a plurality oflight sources 220 arranged in arrays. As indicated in FIG. 2A, the lightsources 220 are equidistantly arranged below the LGP 210, and each ofthe light sources 220 corresponds to one sub-illuminating region L onthe LGP 210. In this embodiment, the distance between two adjacent lightsources 220 is relevant to the optical design of the light sources 220.People having ordinary skill in the pertinent art are able to adjust thedistance between the adjacent light sources 220 based on the opticaldesign of the light sources 220, and the distance between the adjacentlight sources 220 is not limited in this embodiment.

With reference to FIG. 2B and FIG. 2C, each of the light sources 220 ofthis embodiment includes a carrier 220 a, a plurality of solid-statelight-emitting devices 220 b, a light-incoupling component 220 c, afirst reflector 220 d, and a plurality of second reflectors 220 e. Thesolid-state light-emitting devices 220 b and the light-incouplingcomponent 220 c are configured on the carrier 220 a. Thelight-incoupling component 220 c has a bottom surface B, a top surfaceT, a plurality of side surfaces S adjoining the bottom surface B and thetop surface T, and a through hole H extending from the bottom surface Bto the top surface T. The solid-state light-emitting devices 220 b arelocated in the through hole H. The first reflector 220 d covers thethrough hole H. The second reflectors 220 e are configured on the sidesurfaces S of the light-incoupling component 220 c. Light emitted fromthe solid-state light-emitting devices 220 b enters the light-incouplingcomponent 220 c via a sidewall SW of the through hole H and leaves thelight-incoupling component 220 c via the top surface T. Besides, thefirst reflector 220 d and the top surface T of the light-incouplingcomponent 220 c are adhered to the light-incident surface 210 a of theLGP 210 via the corresponding optical clear adhesive 230.

The carrier 220 a of this embodiment is a circuit board, for instance.The circuit board is, for example, the well-known FR-4 printed circuitboard, FR-5 printed circuit board, metal core printed circuit board(MCPCB), and so on. Besides, the circuit board can also be a flexibleprinted circuit (FPC).

The solid-state light-emitting devices 220 b are side-view LED packages,for instance. Additionally, the solid-state light-emitting devices 220 bare mounted on the carrier 220 a by surface mount technology (SMT), andthe solid-state light-emitting devices 220 b are electrically connectedto the carrier 220 a, for instance. Moreover, each of the solid-statelight-emitting devices 220 b of this embodiment has a light-emittingsurface E, and each of the light-emitting surfaces E faces the sidewallSW of the through hole H.

In this embodiment, the light-incoupling component 220 c is a squarelight-incoupling component that has a side length ranging from about 10millimeters to about 20 millimeters, for example. The through hole H ofthe light-incoupling component 220 c is a circular through hole (shownin FIG. 2C and having a diameter from about 5 millimeters to about 8millimeters), an elliptical through hole (not shown), or a polygonalthrough hole (not shown), for example. According to other embodiments ofthe invention, the sidewall SW of the through hole H can include aplurality of curved surfaces and a plurality of crest lines exist can beobserved between the curved surfaces, as shown in FIG. 3. In this case,the design of the through hole H enhances uniformity of lightdistribution. The shape of the first reflector 220 d can be adjusted inaccordance with the shape of the through hole H in this embodiment. Thatis to say, the shape of the first reflector 220 d and the shape of thethrough hole H are substantially the same. However, the shape of thefirst reflector 220 d is not limited in this embodiment.

Note that the first reflector 220 d shields and/or reflects the lightemitted from the solid-state light-emitting devices 220 b, such thatmost of the light can enter the light-incoupling component 220 c fromthe sidewall SW of the through hole H and leave the light-incouplingcomponent 220 c from the top surface T. The first reflector 220 d canprevent parts of the light emitted from the solid-state light-emittingdevices 220 b from being directly transmitted in an upward manner andpassing through the corresponding optical clear adhesive 230 and the LGP210. Therefore, the first reflector 220 d can resolve the issue ofexcessively concentrated light above the solid-state light-emittingdevices 220 b. In this embodiment, the first reflector 220 d is areflective plate, and the first reflector 220 d and the top surface T ofthe light-incoupling component 220 c are substantially on the sameplane. However, the horizontal position of the first reflector 220 d isnot limited in this invention. Namely, the first reflector 220 d can beslightly higher than or lower than the top surface T of thelight-incoupling component 220 c.

As clearly shown in FIG. 2B, a gap is between the first reflector 220 dand the solid-state light-emitting devices 220 b. In other words, thethrough hole H for accommodating the solid-state light-emitting devices220 b is not further filled with other materials. Since the medium(e.g., air) in the through hole and the light-incoupling component 220 chave different refractive indexes, refraction occurs when the lightemitted from the solid-state light-emitting devices 220 b passes throughthe sidewall SW of the through hole H, which is conducive to lightscattering. Note that the through hole H can be partially or fullyfilled with an optical filter to cover the solid-state light-emittingdevices 220 b in other embodiments of the invention, so as to furtherprotect the solid-state light-emitting devices 220 b. The optical fillerand the light-incoupling component 220 c should have differentrefraction indexes, such that the light is refracted when passingthrough the sidewall SW of the through hole H.

In this embodiment, the second reflectors 220 e configured on the sidesurfaces S are a plurality of reflective plates or a plurality ofreflective coatings, for instance. The second reflectors 220 e reflectparts of the light entering the light-incoupling component 220 c to thetop of the first reflector 220 d and the solid-state light-emittingdevices 220 b. To be more specific, the light entering thelight-incoupling component 220 c from the sidewall SW of the throughhole H can be categorized into two types. The first type refers to thelight directly passing through the top surface T of the light-incouplingcomponent 220 c, the optical clear adhesive(s) 230, and the LGP 210. Thesecond type refers to the light passing through the top surface T of thelight-incoupling component 220 c, the optical clear adhesive(s) 230, andthe LGP 210 after the light is reflected by the second reflectors 220 e.If the proportion of the two types of light can be arrangedappropriately, the uniform planar light source can be obtained accordingto this embodiment. For instance, people having ordinary skill in theart can selectively make some optical micro-structures on the topsurface 210 b and/or the bottom surface 210 a of the LGP 210, so as touniformize the light distribution on the top surface 20 b of the LGP210. The optical micro-structures are printed dots, V-cuts, or otheroptical micro-structures suitable for scattering light, for instance.

FIG. 4 is a schematic cross-sectional view illustrating a backlightmodule according to another embodiment of the invention. With referenceto FIG. 4, the backlight module 200′ of this embodiment is similar tothe backlight module 200 depicted in FIG. 2B, while the main differencetherebetween lies in that the light source 220′ of the backlight module200′ in this embodiment further includes a third reflective layer 220 fthat is configured between the carrier 220 a and the bottom surface B ofthe light-incoupling component 220 c. The third reflective layer 220 fis a white sheet or any other appropriate reflective plate, for example.

Experimental Example

FIG. 5 shows comparison between optical characteristics according to therelated art and according to an embodiment of the invention,respectively. With reference to the upper-left and the upper-rightirradiance distribution views in FIG. 5, the light source in thisinvention is designed to achieve better uniformity of light distributionin comparison with the conventional light source. In addition, withreference to the lower-left and the lower-right light leakage energydistribution views in FIG. 5, the light leakage issue of the lightsource in this invention is rather insignificant in comparison with thatissue occurring in the conventional light source.

The solid-state light-emitting devices are configured in the throughhole of the light-incoupling component, and the first reflector coveringthe through hole and the second reflectors configured on the sidesurfaces of the light-incoupling component allow the light to be emitteduniformly from the top surface of the light-incoupling componentaccording to this invention. Hence, the light source and the backlightmodule of this invention have favorable optical characteristics.

Although the present invention has been disclosed by the aboveembodiments, they are not intended to limit the invention. Those skilledin the art may make some modifications and alterations without departingfrom the spirit and scope of the invention. Therefore, the protectionrange of the invention falls in the appended claims.

1. A light source comprising: a carrier; a plurality of solid-statelight-emitting devices configured on the carrier; a light-incouplingcomponent configured on the carrier, the light-incoupling componenthaving a bottom surface, a top surface, a plurality of side surfacesadjoining the bottom surface and the top surface, and a through holeextending from the bottom surface to the top surface, the solid-statelight-emitting devices being located in the through hole; a firstreflector covering the through hole; and a plurality of secondreflectors configured on the side surfaces of the plate photo-coupler,wherein light emitted from the solid-state light-emitting devices entersthe light-incoupling component via a sidewall of the through hole andleaves the light-incoupling component via the top surface of the platephoto-coupler.
 2. The light source as claimed in claim 1, wherein thecarrier comprises a circuit board.
 3. The light source as claimed inclaim 1, wherein the solid-state light-emitting devices compriseside-view light-emitting diode (LED) packages.
 4. The light source asclaimed in claim 1, wherein each of the solid-state light-emittingdevices has a light-emitting surface, and each of the light-emittingsurfaces faces the sidewall of the through hole.
 5. The light source asclaimed in claim 1, wherein a shape of the first reflector and a shapeof the through hole are substantially the same.
 6. The light source asclaimed in claim 1, wherein the through hole comprises a circularthrough hole, an elliptical through hole, or a polygonal through hole.7. The light source as claimed in claim 1, wherein the sidewall of thethrough hole comprises a plurality of curved surfaces.
 8. The lightsource as claimed in claim 1, wherein the first reflector is areflective plate, and the first reflector and the top surface of thelight-incoupling component are substantially on the same plane.
 9. Thelight source as claimed in claim 8, wherein a gap is between the firstreflector and the solid-state light-emitting devices.
 10. The lightsource as claimed in claim 1, wherein the second reflectors comprise aplurality of reflective plates or a plurality of reflective coatings.11. The light source as claimed in claim 1, further comprising anoptical filler filling the through hole and encapsulating thesolid-state light-emitting devices, a refractive index of the opticalfiller is different from a refractive index of the plate photo-coupler.12. The light source as claimed in claim 1, further comprising a thirdreflective layer configured between the carrier and the bottom surfaceof the plate photo-coupler.
 13. A backlight module comprising: at leastone light source as claimed in claim 1; a light guide plate having alight-incident surface and a light-emitting surface opposite to thelight-incident surface; at least one optical clear adhesive, the firstreflector of the at least one light source and the top surface of thelight-incoupling component being adhered to the light-incident surfaceof the light guide plate via the at least one optical clear adhesive.14. The backlight module as claimed in claim 13, wherein the carriercomprises a circuit board.
 15. The backlight module as claimed in claim13, wherein the solid-state light-emitting devices comprise side-viewlight-emitting diode (LED) packages.
 16. The backlight module as claimedin claim 13, wherein each of the solid-state light-emitting devices hasa light-emitting surface, and each of the light-emitting surfaces facesthe sidewall of the through hole.
 17. The backlight module as claimed inclaim 13, wherein a shape of the first reflector and a shape of thethrough hole are substantially the same.
 18. The backlight module asclaimed in claim 13, wherein the through hole comprises a circularthrough hole, an elliptical through hole, or a polygonal through hole.19. The backlight module as claimed in claim 13, wherein the sidewall ofthe through hole comprises a plurality of curved surfaces.
 20. Thebacklight module as claimed in claim 13, wherein the first reflector isa reflective plate, and the first reflector and the top surface of thelight-incoupling component are substantially on the same plane.
 21. Thebacklight module as claimed in claim 20, wherein a gap is between thefirst reflector and the solid-state light-emitting devices.
 22. Thebacklight module as claimed in claim 13, wherein the second reflectorscomprise a plurality of reflective plates or a plurality of reflectivecoatings.
 23. The backlight module as claimed in claim 13, wherein theat least one light source further comprises an optical filler fillingthe through hole and encapsulating the solid-state light-emittingdevices, a refractive index of the optical filler is different from arefractive index of the plate photo-coupler.
 24. The backlight module asclaimed in claim 13, wherein the at least one light source furthercomprises a third reflective layer configured between the carrier andthe bottom surface of the plate photo-coupler.
 25. The backlight moduleas claimed in claim 13, wherein a top surface of the light guide platehas a plurality of optical micro-structures.
 26. The backlight module asclaimed in claim 13, wherein a bottom surface of the light guide platehas a plurality of optical micro-structures.